1. Field of the Invention
The present invention relates to a design of a supporting assembly for light-emitting diodes, and in particular to a structure of a supporting assembly for a surface mount device LED and a manufacturing method thereof whereby lenses made in mass production can be assembled with and positioned on the corresponding LED units in one process.
2. Description of Prior Art
Light Emitting Diodes (LEDs) have become widely-used illumination elements because of their advantages such as zero warm-up time, rapid response, small volume, low power consumption, high intensity and long life. Therefore, LEDs are gradually replacing existing lamps and lighting elements used in traffic signs, advertising boards and backlighting modules.
In general, LEDs are formed via the processes of chip fixing, wiring and sealing in a Surface Mount Device (SMD) diode support (referred to as a lead frame), thereby forming a surface mount device LED. The procedure for manufacturing the diode support and the chip-fixing process commonly used in the industry include the following steps:
(a) Pressing process, in which a metallic plate is formed with a plurality of lead regions, and each lead region has two metallic supports that do not communicate with each other.
(b) Injection-forming process, in which an insulating plastic body is injected so that each lead region of the metallic plate is filled with a plastic body to firmly connect to the metallic support. Further, the plastic body is formed with a recessed functional region, and the metallic supports extend outwardly from the functional region to the exterior of the plastic body. In this way, a great number of surface mount device LED supports can be formed on the metallic plate.
(c) Chip-fixing process, in which each lead region of the metallic plate is firmly connected with an LED chip that is connected on the metallic support of the functional region of the plastic body.
(d) Wiring process, in which each LED chip is connected with two wires respectively, and the two wires are connected to the two metallic supports respectively.
(e) Sealing process, in which the functional region of each plastic body is filled with a transparent epoxy resin so as to cover the LED chip and the wires.
Via the above processes, a great number of surface mount device LEDs are formed on the metallic plate. These LEDs can be removed or cut off from the metallic plate easily. Therefore, these LEDs can be welded in the product that is to be assembled. In this way, mass production can be achieved. In order to make the intensity of the LEDs uniform, each LED are provided additionally thereon with a lens that is an optical element having a light-condensing effect. When the light emitted by the LED chip passes through the lens, the light can be condensed, thereby making the intensity of the LED more uniform and enhancing its intensity.
In the prior art, a number of single lenses are manufactured or bought in advance. Then, the metallic plate is fixed on a machine. A robotic arm of the machine grasps each lens to assemble the LED on the metallic plate, thereby combining both of them together. Next, an adhesive is used to adhere and attach the lens onto the LED. Finally, the LED produced by the above procedure is removed from the metallic plate, so that the LED can be assembled with a product.
The abovementioned solution allows the lens to be combined on the LED. However, assembling a single LED results in low production rates, and thus fast/mass production cannot be achieved. Therefore, the production rate (i.e., productivity) is low. Furthermore, the machine has to be precisely positioned so that the lens can be combined on the LED precisely, otherwise defective products will be generated easily, which increases the defection ratio of the manufacturing process and makes the design and operation of the machine more difficult. It goes without saying that the above drawbacks cause a lot of trouble to manufacturers and also results in a number of inconveniences throughout the manufacturing procedure.
Therefore, in view of this, the inventor proposes the present invention to overcome the above problems based on his expert experience and deliberate research.